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Wyszukujesz frazę "Upper Cenomanian" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Mid-Cretaceous spicule-rich turbidites in the Silesian Nappe of the Polish Outer Carpathians : radiolarian and foraminiferal biostratigraphy
Autorzy:
Bąk, M.
Bąk, K.
Ciurej, A.
Powiązania:
https://bibliotekanauki.pl/articles/2058910.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Outer Carpathians
middle-upper Cenomanian
spicule-rich turbidites
radiolarians
foraminifers
biostratigraphy
Opis:
Spicule-rich turbidites are widespread in mid-Cretaceous deep-water flysch of the Subsilesian and Silesian units in the Polish Outer Carpathians. The spicule-richmaterial with an admixture of numerous radiolarian and foraminiferal particles was supplied, together with siliciclastic material, from shallow environments, mostly from the northern margin of the Carpathian Basin. We present new data on the age of these deposits in the Silesian Nappe, where they are distinguished as the Mikuszowice Cherts. This unit is composed of mediumand thick-bedded siliciclastic to calcareous turbidites including bluish cherts in their middle and upper parts and of thin non-calcareous hemipelagic shales.We have studied radiolaria and foraminifera from hemipelagic sediments and spicule-rich turbidites, from two continuous sections in the Barnasiówka Range (BeskidWyspowyMts.) that included theMikuszowice Cherts (31 m thick) and their transition into the surrounding units. The age of the Mikuszowice Cherts was determined taking into account the following radiolarian datum events: (1) the occurrence of Praeconocaryomma lipmanae in the entire unit, (2) the FO (first occurrence) of Hemicryptocapsa tuberosa in the upper part of the unit, (3) the FO of Amphipyndax stocki close to the upper boundary of the unit, (4) the FO of Hemicryptocapsa prepolyhedra in the lowermost part of the overlying Barnasiówka Radiolarian Shale Formation. These datum events appear successively in theWestern Tethys successions within the Rotalipora cushmani planktonic foraminiferal Zone, which corresponds to the middle and upper Cenomanian (except for its uppermost part). The foraminiferal assemblages, in which such taxa as Rotalipora cf. cushmani, R. cf. greenhornensis, whiteinellids and Uvigerinammina praejankoi successively appear, confirm the mid-late Cenomanian age of the spicule-rich turbidites in the Silesian Nappe.
Źródło:
Geological Quarterly; 2005, 49, 3; 275--290
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Siliciclastic input into Upper Cenomanian synorogenic sediments of the High-Tatric Unit, Central Western Carpathians (Tatra Mountains); petrography, geochemistry and provenance
Autorzy:
Wolska, A.
Bąk, K.
Bąk, M.
Powiązania:
https://bibliotekanauki.pl/articles/2060546.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
petrography
geochemistry
Upper Cenomanian
Zabijak Formation
High-Tatric Unit
Central Western Carpathians
Opis:
The Upper Cenomanian mixed siliciclastic-carbonate succession of the High-Tatric Unit was deposited during the initial stage of basinal closing of the Tatric area, part of the Zliechov (Križna) Basin (Inner Carpathian domain). As a result of tectonic activity taking place at the northern Veporic margin, pulses of siliciclastic input interrupted marine carbonate sedimentation. The siliciclastic material, part of the Zabijak Formation, has been studied along two sections (Pisana Gully and Zdziarski Gully) in the Western Tatra Mountains. Microfacies, petrographic and geochemical analyses reveal a variability of siliciclastic material composed of various types of granitoids and medium- or high-grade metamorphic rocks, with schists and gneisses. Such interpretation is confirmed by the results of elemental chemical analyses, in which immobile trace elements, such as REE, Th, Cr, Co, Zr, and Y were used as indices for sediment provenance. The parent rocks sustained moderate to intense chemical weathering, documented by chemical weathering indices (CIA, PIA, CIW, R). The weathering occurred in a humid climate with relatively high precipitation that caused strong leaching of particles. Chemical indices related to sorting processes suggest that the recycling of the source material was a minor significance. The siliciclastic input displays a waning upward tendency in the sections, which can be associated with diminishing of the source area by gradual inland progradation of a carbonate platform, caused by a global sea level rise during the Late Cenomanian.
Źródło:
Geological Quarterly; 2016, 60, 4; 919--934
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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